Recording systems as noted above include indirect electrostatic copying machines utilizing an electrophotographic process, and optical printers such as LED printers. In this type of recording system, generally, the toner transferred to recording paper in the electrophotographic process is maintained in an unfixed condition until the recording paper reaches a fixing device. In order to avoid the necessity to provide a special means for toner adhesion, the recording paper is transported to the fixing device with the recorded side facing up. The recording paper is discharged in the same face-up state after the fixing process. The recording paper thus discharged is stacked with new sheets successively overlying preceding sheets.
According to this arrangement, however, when recording information spanning a plurality of pages is recorded on separate sheets of recording paper, new sheets are successively placed on preceding sheets with their recorded sides facing up. With a machine constructed to start recording the first page of information, the order of page numbering becomes reverse of the proper order of recording information. This requires a manual operation after a recording operation for rearranging the sheets to put the pages in an ascending order from top to bottom.
This rearranging operation is the more troublesome the greater the number of pages of recorded information is. There are recording systems having means for dispensing with the manual rearrangement. One such system includes a reversing device for discharging recording paper face down after a recording operation, thus in the order of page numbering. There is also a type of printer which includes a memory for storing an entire piece of input recording information spanning a plurality of pages, and starts recording the part of the information corresponding to the final page. With this type of printer, therefore, recording paper is discharged face down already in the order of page numbering.
On the other hand, various functions are added to the foregoing recording systems besides the page arranging function in order to promote value added performance.
One of such additional functions is a composite recording function. This function, for example, allows a copying machine to record images of different documents on the same face of a single sheet of recording paper. Further, with this function, a recording system referred to as a digital/analog copier which has both a digital function for recording input recording information dot by dot and an analog function for copying documents can add character or other information to the recording paper on which the image of a document has been formed. To fulfill the composite recording function, a known recording system comprises a paper feeding device for supplying recording paper to a recording section, an image forming device for forming images on the recording paper, a discharge device for discharging the recording paper after the image formation, an intermediate tray for storing plural sheets of recording paper, a branched transport device for feeding the sheets of recording paper after the image formation to the intermediate tray and stacking them face down thereon, and a paper refeeding device for supplying the recording paper from the intermediate tray to the recording section. These paper feeding device, image forming device, branched transport device, paper refeeding device and paper discharge device are operable in response to a composite recording start signal and a recording resume signal. That is, with the composite recording start signal, the recording paper is supplied to the recording section for image formation thereon. Thereafter the recording paper is transported to the intermediate tray. Then, with the recording resume signal, the recording paper is fed from the intermediate tray to the recording section for a further image formation, the paper being discharged subsequent thereto.
Another added function is a duplex recording function. This function, for example, allows a copying machine to record images of different documents on opposite faces of a single sheet of recording paper. Further, with this function, a digital/analog copier having both the digital function for recording input recording information dot by dot and the analog function for copying documents can add character or other information to the reverse side of the recording paper on which the image of a document has been formed. A construction for fulfilling this function is substantially the same as the construction for the composite recording function, and its description is not repeated.
The above known systems with the page arranging function have the following problems.
In the system including the paper reversing device, this device occupies a large space for turning over the recording paper. As a result, the system must have a large overall construction, particularly if the reversing device is provided in addition to an existing paper face-up discharge device. With a printer which simply records input information, compactness may be possible to some extent with an arrangement for stacking recording paper discharged after being reversed by the reversing device on a tray or the like mounted on a top surface of the printer. However, with a copying machine or a digital-analog copier, such a discharge arrangement cannot be employed since a document table is provided on the top surface of the machine. It is especially difficult to provide such a machine with the paper reversing device without the problem relating to space.
Regarding the recording system including a memory for storing information spanning a plurality of pages to start printing the final page, the number of pages of recording information constituting one document is variable and sometimes exceeds one hundred. This means that, in order to realize the page arrangement, a large capacity memory is required to meet the rare recording conditions in which information is recorded on a great number of pages. Such a construction only impairs cost performance and is not practicable. Moreover, such a construction cannot be applied to an ordinary copying machine.
It is also desired for the recording system having the composite and/or duplex recording functions to output recorded sheets in page arrangement. However, a construction such as the foregoing reversing device simply added to realize the page arranging function is futile since it not only complicates the system construction but consumes a very long time in recording information on a large number of sheets.